This is a required, not null field.The identifier must:- Start with the ISO 3166-1 alpha-2 country code, except for Greece ('EL') and the United Kingdom ('UK');- Be followed by the national code, with a maximum of 40 characters; - Use only uppercase letters [A to Z] and digits [0 to 9]. - The underscore character ('_') or the hyphen character ('-') may be used as separators within the code (but not to separate the country code from the national code, and not in the end of the code).

It should be the same identification code as supplied for the previous bathing seasons. If ID numbering has changed, the old identification code should be provided under column "ChangeReason".